This invention relates to an installation structure of an oil control valve, and particularly to an installation structure of an oil control valve which can reduce change of valve characteristics at intervals from the cool state until an engine is in an operating state, which can improve the controlling of a cool oil pressure actuator, and which can improve precision control of an oil pressure control unit.
An engine disposed in a vehicle supplies oil delivered from an oil pump to a dynamic valve, a supplemental apparatus and an oil pressure control unit, and effects lubrication, operation and controlling. For example, as an oil pressure control unit of an engine, there is a variable valve timing apparatus for varying valve timing of intake valve and exhaust valve.
A variable valve timing apparatus consists of an oil pressure actuator arranged at one end of a camshaft, and an oil control valve for supplying oil delivered from an oil pump to the oil pressure actuator. The variable valve timing apparatus supplies oil delivered from the oil pump to the oil pressure actuator by an oil control valve, and varies valve timing of intake and exhaust valves by working the oil pressure actuator.
One example of such arrangement is disclosed in published Japanese Patent Application Laid-Open No. 11-324629. As the installation structure of the oil control valve, in the oil control valve of the 4-cycle engine having a variable valve timing apparatus, the oil control valve is located in the bottom side of a camshaft axis line and in the outside of a timing chain line, and is installed to an engine chain cover.
Incidentally, in an oil control valve of an oil pressure control unit, there is a type supplying oil to an oil pressure actuator by a main valve part that is actuated by a solenoid part.
However, in the oil control valve, the valve characteristics undesirably vary in intervals from the cool state until the engine is in an operating state because the solenoid part generates heat when electrically energized. In addition, the oil control valve causes a reduction of control of the oil pressure actuator supplied oil, as a result, there is reduced controlling accuracy of the oil pressure control unit.
To obviate or minimize the above inconvenience, the present invention provides an installation structure of an oil control valve, wherein a timing chain transmits rotation of a crankshaft of an engine to camshafts, a chain cover is installed to the engine so as to cover the timing chain, a cooling fan rotated by the crankshaft is located forward of the front part of the chain cover, an oil pump driven by the crankshaft is arranged, an oil control valve which supplies oil delivered from the oil pump to an oil pressure actuator for an oil pressure control unit is located, and the oil control valve is installed to a front part of the chain cover in the rotational trace of the cooling fan. As a result, the installation structure of the oil control valve can reduce changes of valve characteristics in intervals from the cool state until the engine is in an operating state, and the controlling of cold oil pressure actuator is improved, and the controlling accuracy of an oil pressure control unit is improved.
In the installation structure of an oil control valve of this invention, because the oil controlling system is installed on a front surface of a chain cover so as to be located in the rotation air flow trace of the cooling fan rotated by the crankshaft, the oil control valve can be positively cooled by cool wind from the cooling fan, thereby reducing change of valve characteristics at intervals from the cool state until the engine is in an operating state.